Although applicable to any system that reproduces sound, the present invention will be described in combination with display devices with integrated sound generation means.
In modern display applications it is not only necessary to display visual content via a display. It is frequently further required to reproduce together with visual data corresponding audio data, e.g. to play a video. Therefore, known display devices are usually equipped with separate internal or external speakers to reproduce audio content. Incorporating speakers in e.g. a mobile phone or a television requires additional space in the housing of the respective device and the speakers must be positioned adequately to reproduce the sound with acceptable quality.
Therefore, displays have been developed where the whole display, i.e. the front surface of the respective device, is vibrated by a vibration device to generate sound waves.
Such transducers are needed to mechanically touch a front surface of the respective display. This can be achieved by an additional opaque panel which surrounds the display and is vibrated by a respective transducer, which is placed beside the display unit. But this option increases the bezel size which is an unwanted effect.
Alternatively an additional transparent panel can be used in front of the display. But this decreases overall luminance of the display.
It is further known from document US 2014/0 241 558 to vibrate the whole screen including front glass, cell and BLU assembly. Further, in WO 2001/074114 segmented LCD displays are separately vibrated.
Document EP 1 100 288 A2 discloses an acoustic radiator, which includes a plate-like member, which has elastic properties in a driving frequency band for acoustic radiation. Document EP 0 847 677 A1 discloses an inertial vibration transducer characterised by a plate-like piezo-electric bender and means adapted to mount the bender on a member to be vibrated. Document US 2015/0 086 063 A1 discloses a speaker, which includes a hollow glass substrate and a plurality of vibration exciters, where the vibration exciters are attached to the glass substrate to drive the glass substrate to vibrate.
Accordingly, there is a need for an improved method of reproducing sound with a display device.